With the requirement for the use of Exhaust Gas Recirculation (EGR) for emission purposes in motor vehicles, the original valves were responsive to a temperature control to cause the valve to open fully when EGR was required. As more sophistication in motor vehicle control systems developed, the control of the EGR valve became more important and more refined. The electronic control unit or on-board computer in the vehicle responding to signals from various sensors, generated pulse width signals to modulate or cycle the EGR valve as required. However, the valve still had only one open and one close position.
A binary encoded and operable EGR valve having better control of the amount of gas recirculation by having a plurality of solenoid actuated valve ports is described in now abandoned U.S. patent application having Ser. No. 659,501 entitled "Electro-Mechanically Controlled EGR Valve and Method" and filed by John E. Cook on Oct. 10, 1984. The above application is a continuation of U.S. Ser. No. 536,475 filed on Sept. 28, 1983 now abandoned.